What is Wakabayashilite?
Wakabayashilite is a rare arsenic sulfide mineral, typically yellow to orange-brown and associated with fumarolic or epithermal arsenic deposits.
Mineralogy and structure
Reference formula: As10S14. Wakabayashilite is orthorhombic and natural material may include antimony substitution. COD 9003699 is used as a labelled representative model for the arsenic sulfide structure. Wakabayashilite is classified with sulfosalts and has orthorhombic crystal symmetry. Typical hardness is 1.5–2 on the Mohs scale and specific gravity is approximately 3.6–3.9.
Colour, lustre and habit
Typical colours include yellow, orange-yellow, brown, red-brown. The usual prismatic, granular, massive habit and resinous, adamantine, dull lustre help describe a specimen, but colour alone is not diagnostic.
Formation and notable localities
Wakabayashilite forms in or is associated with arsenic-rich hydrothermal veins, fumarolic environments and oxidised antimony-arsenic deposits. Important documented localities include Japan, the United States, Mexico, Russia and other arsenic-rich localities.
Golden arsenic sulfide from a rare ore setting
Wakabayashilite is collected for its unusual yellow colour and rarity, but responsible presentation requires the same care as other arsenic-bearing sulfides.
Collecting and care
Arsenic-bearing and soft: keep sealed, dry and away from dust, food and children; do not grind, heat or acid-test.
